Stripping agent



Patented Oct. 29, 1935 UNITED STATES STRIPPING AGENT John Gwynant Evans and Leslie Gordon Lawrie,

Blackley, Manchester, Imperial Chemical ration of Great Britain England,

' Industries Limited, a corpo- No Drawing. Application April 2, 1934, Serial No.

9 Claims.

In British Specification No. 400,239 there is described a process for the stripping of textiles dyed with azoic colours comprising the treatment of the dyed materials with a reducing liquor containing an amine or amine salt, one radical in which comprises a straight or branched carbon chain of not less than 10 carbon atoms.

The present invention relates to the stripping of textile fibres dyed'with alizarine colours, applied by the usual mordant method, basic colours and vat colours as herein defined.

The invention has for its object the provision of a. technically advantageous, economical process of stripping, particularly adapted to the entire or substantially entire removal of solid shades provided by alizarine colours, dyed by the usual mordant methods, basic colours and vat colours.

This object is accomplished according to the invention by treating textile material dyed with the said colours in a liquor containing an amine or amine salt, preferably a quaternary ammonium salt, one radical in which comprises a straight or branched carbon chain of not less than 10 carbon atoms, and also containing where advantageous one or more of the following additional substances, namely, acid, alkali, reducing agent, soluble soap and a sulphonic acid or sulfuric ester as herein defined.

The additional substances may be added or not according to the dye and the textile materials from which it is to be stripped. With basic colours it is usually sufiicient to heat in an aqueous liquor with the amine salt or with the amine in a medium containing a little acid. With alizarine colours a reducing agent is usually necessary to give a bath which will reduce the colours. With vat colours an alkali and reducing agent, preferably together with a soluble soap, or a sulphonic acid or sulfuric ester as hereinafter defined is used. When stripping wool and silk and other animal fibres some risk of injury to the fibre is present if alkali is used so alkali is preferably avoided. The acid may be mineral or organic acid. The fibre is stripped white or slightly tinged. In the latter case, for vegetable fibre a supplementary chlorine or chemic treatment may be applied further to improve the ground. In the case of animal fibre a supplementary peroxide treatment is sometimes beneficial.

In stripping in the presence of a reducing agent the amine or amine salts referred to above as well as increasing this degree of stripping also retard the rate of re-oxidation of the reduced dyeings thus giving more even stripped shades, where stripping white is not required,

In Great Britain April 7, 1933 Suitable amines or amine salts are for example p-di-ethylamino-ethyloleyl amide or its acetate or hydrochloride, heptadecylamine or its hydrochloride (Hofiman, Berichte, 1882, 15, 774) and suitable quaternary ammonium salts are, for example, 6

soluble salt thereof, where R is an aliphatic satu- 25 rated or unsaturated radical containing a. carbon chain of not less than 10 carbon atoms. Advantages of our invention are that it provides a ready means of stripping Turkey red and other alizarine mordant colours and vat dyes which are normally very difiicult to strip: that it provides a very simple means of stripping basic colours and that all these colours, together with azoic colours can be stripped by the same liquor. When we speak of dyed textile materials we include also printed textile material but we do not include discharging, that is to say the local removal of colour for the purpose of making coloured patterns.

The following examples in which parts are by weight illustrate but do not limit the invention. Example 1.A dyeing of Turkey red on cotton is treated for 30 minutes at the boil with 40 times its weight of an aqueous solution prepared by adding 4 parts of caustic soda, 3.75 parts oi sodium hydrosulphite and 2 parts of trimethylcetylammonium bromide to 1000 parts ofwater. The material is stripped to a pale brown shade which can be cleared to a white by treatment ior 15-30 minutes in /2 tw. sodium hypoch'lorite." Example 2.-A 1% shade of Auramine Q (Colour Index No. 655) dyed on tannin rno'rdanted cotton in the usual manner is treated for hour at the boil in a 0.17% aqueous solution of octadecylpyridinium bromide. The dyestufl is completely removed from the fibre.

Example 3.--A 1% shade of Rhodamine BGBS (Journal of Soc. 0! Dyers and Colourists, 1933, vol. 40, page 110) dyed on tannin mordanted cotton in the usual way is treated for 95 hour in 0.17% aqueous solution of trimethylcetylammonium bromide. The cotton is stripped to a very pale pink shade.

Example 4.As Example 2 but a 1% dyeing oi Magenta P (Colour Index No. 677) is treated in a 0.17% aqueous solution of the acetate of the asymmetrical diethylaminoethylamide of oleic acid. The dyeing is stripped to a very weak bluish red shade.

Example 5.-A 1% shade of Acronol yellow T (Colour Index No. 815) dyed on silk in the usual manner is treated for hour at the boil in a 0.17% aqueous solution of trimethylcetylammonlum bromide. The silk is stripped to a very pale yellow shade. v

Example 6.-A 1% shade of Auramine 0 (Colour Index No. 655) on silk is treated as in Example 5. The dye is almost completely removed from the'iibre.

Example 7.Cotton yarn dyed with 10% Caledon yellow (3 (Colour Index No. 1118) is treated for minutes at 95 C. with 40 times its weight of an aqueous solution prepared by adding 5 parts of caustic soda, 4 parts of sodium hydrosulphite (conc. powder) and 2 parts of benzyldimethylcetylammonium chloride to 1000 parts or water.

The yarn is stripped to a very pale yellow shade.

Example 8.--Cotton yarn dyed with 10% Durlndone blue 4BC (Colour Index No. 1184) is treated as in Example '7, but using benzyldimethvlcetylammonium sulphonate instead of the quaternary ammonium salt there mentioned.

The yarn is stripped to a weak blue shade.

Example 9.Cotton yarn dyed with 15% Caledon blue R (Colour Index No. 1106) is treated as in Example 'l but using trimethylcetylamgclmium bromide as the quaternary ammonium The yarn is stripped to a pale blue shade, which, ii desired, can be stripped white by treatment for 1 hour in 1 tw. sodium hypochlorite solution.

Example 10.-Cotton yarn dyed with 10% Caledon jade green paste (Colour Index No. 1101) is treated for 30 minutes at 90-95" C. with 40 times its weight of an aqueous solution prepared by adding 5 parts of caustic soda, 4 parts of sodium hydrosulphite (cone. powder), 0.5 parts of trimethylcetylammonium bromide and 0.4 parts of oleic acid, to 1000 parts or water.

The yarn is stripped to a weak green shade.

A similar effect is obtained by substituting textile flakes or cetylsodium sulphate, or the oleic ester oi! taurine for the oleic acid.

Example 11.Cotton piece goods dyed with 3% pa-naphthothio-indigo are treated for 30 minutes at 90-95 C. with 40 times their weight of an aqueous solution prepared by adding 5 parts of caustic soda, 4 parts of sodium hydrosulphite (conc. powder), 1 part of trlmethylcetylammonium bromide, 0.8 parts 01' oleic ester of taurine to 1000 parts water.

The material is stripped to a white.

Example 12.-Cotton yarn dyed with 20% Caledon yellow 3G (Colour Index No. 1132) is treated for 30 minutes at 90-95 C. with 30 times its weight oi an aqueous solution prepared by adding 2.0 parts of caustic soda, 3.33 parts of sodium hydrosulphite (conc. powder) 0,66 parts 01' trimethylcetylammonium bromide and 0.40

parts 01' palmitic acid to 1000 parts or water.

The yarn is squeezed and treated for 15 minutes in tw. sodium hypochlorite solution.

iollowed by a souring treatment with A tw. hy- 6 drochloric acid. The yarn is stripped to a very weak yellow shade.

Example 13.-A 20% dyeing of Durindone pink Fl". Colour Index No. 1211 on a cotton piece is treated as in Example 12. The material is 10 stripped to a very'weak pink shade.

Example 14.-A 20% dyeing oi Caledon Jade green (Colour Index No. 1101) on viscose yarn is treated as in Example 6.

The material is stripped to a weak green shade. 15

Example 15.-A 20% dyeing oi. Caledon blue RC (Colour Index No. 1114) on viscose yarn is treated as in Example 12.

The material is stripped to a weak blue shade.

Example 16.-Wool dyed a full red with alisarine on an aluminium mordant is treated for 20 minutes at the boil in a solution containing 2 parts oi! cetyltrimethylammonium bromide, 2 parts 0! acetic acid (30%) and 4 parts of sodium formaldehyde sulioxylate, in 1000 parts of water. 25

It is stripped to a very pale pink colour.

We claim:

1. A process for stripping textile materials dyed with colours selected from the group consisting of alizarine colours, basic colours and vat colours which comprises treating them with a liquor containing a substance selected from the group consisting of amines and amine salts having an aliphatic radical which contains not less than 10 carbon atoms. a

2. A process for stripping textile materials dyed with colours selected from the group consisting of alizarin'e colours, basic colours and vat colours which comprises treating them with a liquor containing a cetyltrialkylammonium salt.

3. A process for stripping textile materials dyed with colours selected from the group consisting of alizarine colours, basic colours and vat colours which comprises treating them with u a liquor containing cetyltrimethylammonium bromide.

4. A process for stripping textile materials dyed with colours selected from the group consistsing or alizarine colours, basic colours and o vat colours which comprises treating them with a hot dilute liquor containing cetyltrimethylammonium bromide.

5. A process for stripping textile materials dyed with vat colours which comprises. treating them with a chemically reducing liquor containing a substance selected from the group consisting of amines and amine salts having an allphatic radical which contains not less than 10 carbon atoms.

6. A process for stripping textile materials with vat colours which comprises treating them in alkaline chemically reducing liquor containing cetyltrimethylammonium bromide and a soluble soap. .5

. 7. A process for stripping materials dyed with vat colours which comprises treating them in alkaline chemically reducing liquor containing cetyltrimethylammonium bromide and a substance selected from the group consisting of 1 RSOJH and ROSOSH where R. is an aliphatic radical which contains not less than 10 carbon atoms.

8. A process for stripping textile materials dyed with aiiaarine colours which comprises ya treating them with a chemically reducing liquor dyed with alizarine colours which comprises containing a substance selected from the group treating them with a chemically reducing liquor consisting of amines and amine salts having an containing cetyltrimethylammonium bromide. aliphatic radical which contains not less than 10 5 carbon atoms. JOHN GWYNANT EVANS.

9. A process for stripping textile materials LESLIE GORDON LAWRIE. 

